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Chapter 7

PSYC 235 Chapter 7: PSYC235B Chapter 7 Part 2

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Queen's University
PSYC 235
Christopher Bowie

Causes of Mood Disorders • Consider the interaction of biological, psychological and social dimensions • Also notes very strong relationship between anxiety and depression Biological Dimensions Familial and Genetic Influences • Family Studies • Look at prevalence of the disorder in first-degree relatives of an individual (proband) • Both unipolar depression and bipolar disorder run in families • Rate in relatives of probands with mood disorders is 2-3x greater than relatives of controls who don’t have mood disorders • Also showed that increased severity and recurrence of MDD in proband was associated with higher rates in relatives • Adoption Studies • If genetic contribution exits, adopted probands with the disorder should have more biological relatives with the disorder than adopted probands without the disorder • Studies show contradicting results • Some report greater risk of mood disorder among biological relatives of adoptees with mood disorder • Other study showed no greater risk • Twin Studies • Examine identical vs fraternal twins • If genetic contribution exists, should be present in identical twins to much greater extent • One study demonstrated that identical twin is 2-3x more likely to have mood disorder if the first twin does • If one twin has unipolar disorder the chances of a co- twin having it are slim to none Sex Differences Study (1999) -> studied 2662 twin pairs and found characteristically higher rate of depressive disorders in women – estimated heritability was 36-44% for women but for men, 18-24% • Bipolar disorder confers risk of developing some mood disorder, but not necessarily same one • If one identical twin is unipolar, other twin has 80% chance of being unipolar too • Most genetic vulnerability to bipolar disorder is specific to bipolar syndrome • McGuffin and colleagues found that individuals with bipolar disorder are genetically susceptible to depression and independently susceptible to mania • Genetics of mania is different from depression in bipolar disorder, but same for depression • Reflect at least a little bit of genetic vulnerability, especially for women • Unlikely to find dominant gene responsible for this • CONCLUSION: genetic contributions are ~40% for women, significantly less for men • Contribution for bipolar disorder somewhat higher • Means that ~60-80% of causes of depression attributed to environmental factors Joint Heritability of Anxiety and Depression • Family studies indicate that the more signs and symptoms of anxiety and depression a patient has, the higher rate of these disorders in first-degree relatives and children Kendler Heritability Study (1995) -> studied 2000 female twins and found that same genetic factors contribute to both anxiety and depression. Suggests that vulnerability for mood disorders may not be specific to that disorder – may reflect more of a general predisposition to disorders or underlying emotional temperament, like neuroticism. • Specific form of the disorder would be determined by unique factors (psychological, social etc) Joint Heritability of Anxiety and Depression • Research implicated low levels of serotonin in the etiology of mood disorders, but only in relation to other neurotransmitters like norepinephrine and dopamine • Main regulatory function of serotonin: regulate emotional reactions • Functions to regulate systems involving norepinephrine and dopamine • Permissive Hypothesis • Serotonin low  other neurotransmitters range more widely  dysregulated  mood irregularities Mann and Colleagues (1996) -> used brain imaging procedures (PET) to confirm impaired serotonergic transmission in depressed patients. Follow up research says this only holds true for more severe cases where patients have suicidal tendencies • What seems to be most important is the balance of various neurotransmitters and their subtypes than the absolute level of any one • Interest in dopamine and the relationship to manic episodes, atypical depression or depression with psychotic features • Dopamine agonist, L-dopa (and others)  hypomania in bipolar patients • Chronic stress reduce levels of dopamine and produces depressive-like behaviour The Endocrine System • Researchers saw patients with diseases affecting this system sometimes become depressed • Hyperthyroidism  affects adrenal cortex  excessive secretion of cortisol  depression • Recall that the HPA: begins in hypothalamus and runs through pituitary • Adrenal gland produces stress hormone cortisol • Levels are elevated in depressed patients • Thought to have developed a biological test for depression: dexamethasone suppression test • Oversecretion of cortisol thought to overwhelm suppressive effects of dexamethasone • When dexamethasone given to depressed patients, much less suppression was noticed • 50% show reduced suppression, especially if severe • Later research showed that other disorders, like anxiety, also produce this response • Discovered that neurotransmitter activity in the hypothalamus regulates the release of hormones from the HPA axis • Neurohormones (we have 1000s) and their effect on CNS is area of interest Sleep and Circadian Rhythms • In those who are depressed, much shorter period after falling asleep before REM sleep • Typically, after 90 minutes, begin to experience REM sleep and as the night goes on, hae increased amounts of REM • Depressed patients have increasing amounts, more intense REM and slow wave sleep doesn’t happen until later, if at all • Issues with sleep continuity and reduction of sleep may happen when depression is not present • Sleep disturbances in children less evident (because they are deep sleepers) • Insomnia is a risk for onset and persistence of depression • Found that treating insomnia in patients with both insomnia and depression may enhance effects of treatment • In bipolar patients: severe sleep disturbances like decreased REM and severe insomnia and hypersomnia • Relationship between mood and sleep is bidirectional in both groups • Negative mood  sleep disruptions  negative mood • Depriving depressed patients of sleep, especially during second half of night, improves condition temporarily, but returns when normal sleep returns • May be relationship between SAD, sleep disturbances and general disturbance in biological rhythms • Most mammals sensitive to day length, latitudes etc • Problematic to vulnerable individuals • Tend to have poorer response to psychological treatment Additional Studies of Brain Structure and Function • Depressed individuals exhibit greater right-sided anterior activation of their brains, especially prefrontal cortex • Less left sided activation = less alpha wave activity • Also found in those who were no longer depressed so, may exist before • Adolescent offspring of depressed mothers showed this pattern suggesting possible vulnerability • Shown that bipolar spectrum patients have elevated left-frontal EEG activity • May predict onset of bipolar I disorder • Studying anterior cingulate cortex and amygdala for cues to understand brain function in people with depression – finding some areas more, and others less, active • Areas all interconnected • Associated with increased inhibition and deficits in perusing desired goals Psychological Dimensions Stressful Life Events • Stress and trauma among most striking unique contributions to the etiology of all disorders • Investigators have stopped asking if stressful event has happened to patient – instead ask what meaning the event has on the person • Example: losing a job when your spouse is making more than enough may not be stressful to you, but can be very stressful if you are a single mom • Same event, but context is very different and transforms the significance of the event • Best way to study stressful life events is prospectively because descriptions may become distorted due to current emotions and depression • Severe events precede nearly all cases of depression • For people with recurrent depression, clear occurrence of a severe life stress before or early in latest episode = much poorer response to treatment, longer time before remission and greater chance of re-occurrence • Romantic relationships play a key role in adolescent depression • Based on the gene-environment correlation model • Example: people who tend to seek out difficult relationships because of genetically based characteristics that lead to depression • Kendler et. al report that 1/3 of association between stress and depression is due to individuals vulnerable to depression that place themselves in high-risk, stressful environments • Also strong relationship for bipolar disorder • Early life stress seems to trigger mania and depression and disorder continues • Provoke relapse and prevent recovery • Most people who experience stressful life events do not get depressed – between 20-50% Learned Helplessness • Seligman says that people become anxious and depressed when they make an attribution that they have control over the stress in their lives • Evolved into the learned helplessness theory of depression • Anxiety may be first reaction to stress  hopelessness  depression • Depressive attributional style is: 1. Internal: individual attributes negative events to personal failings 2. Stable: even after negative event passes, think that additional bad things will be their fault 3. Global: attributions extend to variety of issues • Is this a cause of depression or correlated side effect? Nolen-Hoeksema, Girgus and Seligman (1992) -> conducted 5-year study in children that showed negative attributional style did not predict later symptoms of depression in young children; rather, stressful life events did. As they grew, developed more negative cognitive styles, predicting depression. • Negative events in childhood  negative attributional styles  more vulnerable to future depressive episodes • In people with genetic vulnerability, stressful events activate a psychological sense that life events are uncontrollable • This type of thinking and negative attributional style theorized to contribute to anxiety disorders • Not specific to one mood disorder • Later revised to highlight sense of hopelessness as crucial cause to many forms of depression • Both anxious and depressed individuals feel helpless and believe they lack control, but only in the latter do they become hopeless about regaining control ever again • Pessimistic style of attributing negative events to our own character flaws results in hopelessness • John Abela of McGill U found results to support this theory based on study of Grade 7 students Negative Cognitive Styles • Beck suggested that depression may result from tendency to interpret everyday events in a negative way • Smallest setbacks = major catastrophes • Two representative examples: • Arbitrary inference is where depressed patient explains negative rather than positive aspects of a situation • Overgeneralization is where you extend one small remark to a bigger picture, like getting a bad grade and thinking you will fail the class despite many more positive comments • Think like this about themselves, immediate world and their future: the depressive cognitive triad • May develop deep-seated negative schema (Ex. Self-blame schema, negative self-evaluation schema) – Beck said these were unconscious thinking • Thinking of depressed individuals is more negative in each area of the triad • In a study, depressed group attributed many more negative traits (ex. Stupid, boring) and less positive traits (ex. Attractive, nice) to themselves • When in remission from an episode, no longer think this way • Depressed patients more likely to select target expression that were both positive and negative • Have less access to positive social information about themselves, but not other people • These cognitive biases were studied and shown to decrease in those who had recovered (6 months later) when actively depressed • BUT still showed interconnectedness of negative material at both testing times • Consistent with Beck’s schema hypotheses because they are stable and activated by negative events • Higher levels of negative interconnectedness and lower levels of positive • Beck’s theory is critical!! • He became the father of cognitive therapy Cognitive Vulnerability for Depression: An Integration • Seligman and Beck have independent theories with good evidence for each • Some people may have negative outlook (dysfunctional attitudes) • Others may express things negatively (hopeless attributes) • Overlap a lot Social and Cultural Dimensions Marital Relations • Marital disruption often precedes depression Bruce and Kim (1992) -> collected data on 695 women and 530 men; 21% of women who reported a marital split experienced severe depression (3x higher than married); 17% of men who split experienced severe depression (9x higher than married) • However, only the men faced a heightened risk of developing mood disorder for first time following a split • Need to separate marital conflict from marital support • Possible that high conflict and high support present at same time, or absent at same time • High conflict & low support particularly important in generating depression • If depression continues may lead to deterioration of marital relationships • Being around someone who is negative, ill-tempered, pessimistic etc lead to arguments and negative interactions • Depression causes men to withdraw from marriage • For women, it is problems in relationship that cause depression • People with bipolar disorder less likely to get married, more likely to get divorced, but if they stay married  have better prognosis because of spousal support Mood Disorders in Women • 70% of individuals with depression and dysthymia are women – constant all over the world • Similar ratio for most anxiety disorders • Even amount for bipolar disorder • Gender differences may be strongly influenced by perceptions of uncontrollability • If you have a sense of mastery over your problems, you may not feel helpless • Source of these differences is cultural as males are encouraged to be independent, masterful and assertive; opposite for females • Still describe sex roles to a large extent today • Gender roles in parenting implicated in psychological vulnerability for children too (ex. Smothering, overprotective parenting style) • Value that women place on intimate relationships may put them at risk when problems start to happen, but if reaches stage of divorce, more impactful for men (as mentioned above) • Majority of people living in poverty in North America are women and children, particularly single moms • Depression 2.5x higher in single women with a child under 5 years old • Married women, employed full time, have no different rates • Work stress associated with both men and women, but gender influences the type of stress • Psychological demands for male and physical demands for females • Abuse histories – strong link between early sexual abuse and comorbid anxiety and depression • In 60 females with depression, 65% reported sexual violation at some point in life • Disorders associated with aggression, over activity and substance abuse more prevalent in men Social Support • Risk of depression for people who live alone is 80% higher Brown and Harris (1978) -> landmark study found that only 10% of women had a friend to confide in became depressed compared to 37% who did not have a friend • Importance of social support in recovering from depression • Women who had social support from spouse for postpartum depression showed significant decrease in symptoms of depression • Socially supportive network helped recovery from depressive episodes but not manic episodes An Integrative Theory • Depression and anxiety share a common genetic vulnerability – response to stress • Serotonin transporter gene • Vulnerability in general, not for one particular disorder • Stronger for women than men • Also possesses psychological vulnerability in feelings of inadequacy for coping with difficult stress • When triggered, giving up process seems crucial in development of depression • Traced back to childhood events (ex. Depressed mothers, abuse etc) • Stressful events trigger CRF system that can turn on certain genes and chemically change brain • Example: may lead to atrophy of neurons in hippocampus • Circadian rhythms, negative thinking, learned helplessness, interpersonal relationships, our gender Treatment • Principal effect of medications is to alter levels of these neurotransmitters and neurochemicals • Powerful psychological treatments also alter brain chemistry • Most cases go untreated because neither health-care professionals nor patients recognize depression or symptoms Medications • 3 basic types of antidepressants • Tricyclic antidepressants • Widely used – best known are imipramine (Tofranil) and amitriptyline (Elavil)s • Block reuptake of certain neurotransmitters  pool in the synapse  desensitize or down regulate the transmission of that particular neurotransmitter • Greatest effect downregulating norepinephrine, but serotonin also affected • Complex effect on presynaptic and postsynaptic regulation • Restoring p
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